1. Technical Field
The present invention relates to the connection between a visual display and the main body of a portable computer.
2. Discussion of the Related Art
Portable computers, such as lap-tops, are being used increasingly as more and more people require mobility in performing work duties. Generally, a portable computer includes a body portion with a keyboard and display portion rotatably mounted on one side of the body portion such that the display portion can spread open from the body portion. The display portion, including a liquid crystal display (LCD), is rotated to define an opened or closed position relative to the body portion with a rotatable hinge assembly fixed on the body portion.
Exemplars of the contemporary practice in the art include U.S. Pat. No. 5,379,183 for Combination I/o Plate/Lid Hinge Structure for a Notebook Computer issued to Okonsky et al., which includes a bottom-mounted hinge bracket with mounting tabs connected to circuit boards of the computer system as well as to an I/O plate. U.S. Pat. No. 5,566,048 for Hinge Assembly For a Device Having a Display issued to Esterberg et al., includes a hinge mechanism with an attachment boss that mounts on the bottom surface of a computer case. The hinge does ground the main board. U.S. Pat. No. 5,195,213 for Hinge Device for Coupling Rotatable Member to Another Member issued to Ohgami et al., includes brackets which mount on the bottom and side, respectively, of a computer housing, to which a shaft is rotatably mounted. The hinges do not ground the main board. U.S. Pat. No. 5,483,253, for Portable Information Processing Apparatus and Liquid Crystal Display Device, issued to Suganuma et al., describes a similar hinge, however, the boss extends from the bottom of the main body housing to a tab extending from the hinge body. U.S. Pat. No. 5,173,837, for Hinge with Two-Toothed Clutch Spring for Suppressing Electromagnetic Interference for Laptop Personal Computer, issued to Blackwell et al., describes a hinge that mounts to the top of a main body housing of a portable computer. U.S. Pat. No. 5,481,430, for Portable Computer Having Keyboard and Coordinate Input Tablet Hingedly Connected to a Main Body Case through a Groove, and U.S. Pat. No. 5,594,619, for Portable Computer Comprising Keyboard and Coordinate Input Tablet Hingedly Connected to a Main Body Case through a Junction Defining a Linear Groove therethrough, both issued to Miyagawa et al., and U.S. Pat. No. 5,237,486, for Structural Frame for Portable Computer, issued to LaPointe et al., describe hinges bolted to the side of a main body housing of a portable computer.
I have found that there is a drawback in the hinge assembly for the typical portable computer because the top case is subjected to undue stresses as it is being opened and subsequently while maintained in an opened state for a long period of time. The stress causes the top case bearing the relatively heavy liquid crystal display to become deformed as a result of the weight of the display being concentrated on the hinge-assemblies that are mounted on both sides of the top case so that the display portion is supported only by the top case. This problem is aggravated when the top case is thin and weak.
I have noticed that another drawback of the typical portable computer is that electromagnetic interference (EMI) is not fully shielded. Electromagnetic waves from the main circuit board are not sufficiently blocked because the main circuit board is joined only to the bottom of the computer's case, thus inadequately grounding any induced current. This results in substantial electrical interference with electromagnetic waves processed by other elements in the computer. Also, there is a risk that these electromagnetic waves are harmful to humans.